The chemistry of cyclometalation : a comprehensive study on cycloiridated 1-arylalkylamine and imine complexes
Chen, Jeremy Houguang
Date of Issue2018
School of Physical and Mathematical Sciences
As fundamental ligand frameworks within the field of cyclometalation, the 1-arylalkylamine and imine motifs have a widespread presence as cyclometalating ligands for an extensive number of transition metal elements. In the thesis, we investigate the outcome of cycloiridation of various 1-arylalkylamine and imine ligands with [IrCp*Cl2]2. A good balance of steric factors within the organic scaffold was found to be vital for the formation and stability of amino-derived iridacycles. While excessive steric hindrance would lead to numerous side reactions affording an assortment of byproducts, the lack of steric bulk within the amine ligands would lead to an internal oxidation to its imine functionality within the cyclometalated ring. Investigations into the failed cyclization procedure revealed a consistent competing pathway leading to either a strained ring system or an iminium species. The postulated intermediates can then readily undergo hydrolysis to provide a N-dealkylated amine moiety and a carbonyl compound. Optically-active cycloiridated complexes from successful direct ortho-metalation procedures were characterized for its conformational lock and evaluated for its efficiency in the catalytic asymmetric hydrogen transfer reaction. Lastly, we examine the crystallographic structures of the synthesized iridacycles to gain insights into their bonding.